Configures an analog input channel independent of the
 type of physical Ai-card. The conversion from signal
 value to actual value is done by polynomials.

 Figure below shows the steps in Ai-signal conversion and
 attributes of interest. The internal filtering concerns local
 Ai signals, i.e remote Ai-signals are not affected.

 Quantities of Importance for Handling Ai Signals

 SigValue is converted to ActualValue via sensor
 function s, sensor polynomial p and filter function f
 according to,
         ActualValue = f ( p( s(SigValue) ) ) , where
 the choice of

         -- sensor function s, is determined by SensorTypeCode
         -- sensor polynomial p, is determined by  SensorPolyType
         -- filter function f, is determined by FilterType in Ai object

 For linear conversion the conversion from rawvalue to engineering value can be
 specified by four ranges

 - raw value range            RawValRangeLow - RawValRangeHigh
 - channel signal value range ChannelSigValRangeLow - ChannelSigValRangeHigh
 - sensor signal value range  SensorSigValRangeLow - SensorSigValRangeHigh
 - actual value range         ActValRangeLow - ActValRangeHigh

Raw value is the value read by the card or received from the bus. This converted to
the signal value of the channel, typically +/-10 V, +/-5 V or +/-20 mA. The part of
this range that is actually utilized by the sensor, that could be for example 4-20 mA
is then converted to engineering unit.

 ChanAi objects are configured below a suitable card
 object.

 Rack and card objects to different I/O systems are
 documented separately.
 To create card object with channel objects belonging to
 it the function 'Configure Card' in "Utility Window" is
 recommended.

• ChanAit

 Optional text, for example to describe the channel or
 its employment.

 Name of a signal object, i.e. Ai object, connected with
 the channel object.

 The identity of the channel. Optional, for example Ai0
 to denote the first channel, physical cable marking,
 etc.

 The Number attribute is used to associate the ChanAi
 object to a fixed channel on the card named by
 SigChanCon. The physical channels of the card are
 numbered in the interval {0,1, ... , (MaxNoOfChannels-1)},
 where MaxNoOfChannels is an attribute in the card
 object.
 The channels of the card are numbered according to the
 instructions of the card manufacturer.

 Specifies if the RawValue should be updated or not.
 FALSE means no updating; TRUE means that RawValue
 should be updated at the period of ScanInterval.

 Specifies, in relation to the period T0, how often
 RawValue will be read in and converted to ActualValue.

 The IO job handles local Ai-signals by the period T0 =
 CycleTimeBus and remote signals by the period T0 =
 CycleTimeSerial; see IOHandler).
 ScanInterval have to be >= 1.

 RawValue will be updated by the period: ScanInterval * T0.

 The Low and High values of RawValRange specifies the
 raw value range of the channel.

 The Low and High values of ChannelSigValRange specifies the
 signal range of the channel.

 Engineering unit for SigValue, for example Voltage.

 Obsolete.

 Specifies in which way SigValue will be converted to
 ActualValue. The possible types of conversions are:

   0   No conversion
   1   Linerar converson.
   2   Parabolic conversion.
   3   Squareroot conversion.
   4   Signed squareroot conversion.

 The constant term in a SensorPolyType expression; see
 above.

 The Low and High values of SensorSigValRange specifies the
 part of the ChannelSigValRange that is used by the sensor.
 For example, the channel can have a signal range of -20 - 20 mA
 but the sensor only utilizes 4 - 20 mA.

 The Low and High values of ActValRange specifies the
 range of the ActualValue of the signal. These values are
 correlated to the SensorSigValRange.

 Specifies the data representation of the raw value.